There has been an increasing interest in using devices and tools during exercise and athletic activities to enhance performance and also to monitor critical conditions. Measuring physiological characteristics during exercises can optimize workout routines. One such tool is an oximetry unit, which measures the oxygen saturation in blood and pulse rate. During intense exercise or at higher altitudes, there is a tendency for blood oxygen levels to drop. When the body is deprived of an adequate supply of oxygen, generalized hypoxia or tissue hypoxia may occur. Therefore, monitoring blood oxygen levels with an oximetry unit can be used to guide exercise, athletic training, and provide an alarm in critical conditions and situations.
Oximetry is a noninvasive assessment of arterial oxygen saturation (SpO2), which is the measurement of the amount of oxygen carried by hemoglobin in the blood stream. It relies on Beer-Lambert's law, which states that the concentration of an absorbing substance in a solution is related to the intensity of light transmitted through that solution. Accordingly, an oximetry unit uses small light-emitting diodes (LED) to transmit light and then measures the light not absorbed by the tissue by a photodetector to determine the concentration of oxygen in blood. An oximetry unit emits light of at least two different wavelengths, red (660 nm) and infrared (905, 910, 940 nm). Deoxyhemoglobin (hemoglobin not combined with oxygen) has a higher optical extinction in the red region of the light spectrum compared to oxyhemoglobin (hemoglobin that is combined with oxygen). In contrast, in the infrared region, the optical absorption of deoxyhemoglobin is lower than oxyhemoglobin. Thus based on the differences in light absorption, an oximetry unit can measure the amount of light absorbed to calculate the percentage of oxygen saturation in blood.
The oximetry sensor is usually placed on a thin part of the body such as a fingertip or an earlobe. Since oximetry sensors have been predominantly used for clinical or medical purposes, the site of the oximetry sensor placement has generally not been an issue because multiple satisfactory placement sites are readily available. However, during exercise or other athletic activities, traditional locations for oximetry sensor placement such as fingertip or earlobe can be problematic.
It should be appreciated that there remains a need for an assembly that easily measures physiological vital sign changes such as oxygen saturation, pulse, body temperature, and blood pressure of a user during physical exercise, athletic activities, and other critical situations. The present invention addresses this need and others.